1. Technical Field
This disclosure relates generally to a satellite receiver and a satellite navigation system in which satellite state information is used to identify an erroneous satellite.
2. Description of the Related Art
A satellite navigation system (e.g., Global Navigation Satellite System (GNSS)) is a system that estimates the position of a target by using at least one satellite and a satellite receiver. For example, the satellite receiver estimates its position by using satellite navigation information extracted from a satellite signal received from a satellite.
In order to reduce a position estimation error of the satellite receiver, the satellite navigation system transmits satellite state information to the satellite receiver.
FIG. 1 illustrates a configuration for identifying satellite state information in a satellite navigation system according to the related art. The satellite navigation system includes a satellite control center 100, a satellite 110, and a satellite receiver 120. When an error occurs in the satellite 110, the satellite control center 100 transmits “unhealthy” satellite state information to the satellite 110, which is an indication that the satellite is not working properly. Satellite 110 re-transmits the satellite state information, received from the satellite control center 100, to the satellite receiver 120.
Based on the satellite state information received from the satellite 110, the satellite receiver 120 determines whether to use a signal of the satellite 110 for position estimation. That is, when the satellite state is unhealthy, the satellite receiver 120 does not use a satellite signal of the satellite 110 for position estimation.
As described above, the satellite navigation system transmits satellite state information to the satellite receiver 120 through the satellite 110 in order prevent a position estimation error from occurring in the satellite receiver 120 due to the erroneous satellite.
However, a position estimation error of the satellite receiver 120 may increase due to a time delay in identifying an error of the satellite 110. The time delay occurs between the time the satellite control center 100 identifies the error and the time that the satellite receiver 120 receives the satellite state information. For example, when an error occurs in the satellite 110, the satellite receiver 120 is unaware of the error until it receives satellite state information from the satellite 110, and, in the meantime, assumes the satellite 110 is operating normally. Accordingly, a position estimation error may occur in the satellite receiver 120 because the satellite receiver 120 performs position estimation by using a satellite signal received from the erroneous satellite 110, before identifying unhealthy state information of the satellite 110.